Bending machine



p 16, 1969 D. J. GILCHRIST 3,466,914

BENDING MACHINE Filed Nov. 12, 1965 4 $heets,.5heet 1 l l l E 1 l l i Il l u 1 h u INVENTOR.

I 4min I 0801 6212 JGzZc/zrzkf ATTORNEY P 16, 1969 D. J. GlLCHRlST3,466,914

BENDING MACHINE Filed Nov. 12. 1965 4 Sheets-Sheet 2 INVESTOR. 1 AI amdJammy 177' TOKNEY P 16, 1959 1:..1. GILCHRIST 3,466,914

BENDING MACHINE Filed Nov. 12, 1965 4 Sheets-Sheet 5 ATTORNEY Se t. 16,1969 D. J. GILCHRIST BENDING MACHINE 4 Sheets-Sheet 4 Filed Nov. 12.1965 AIR PUMP 88 3 7 girys ijbj I 1M :0. J L1 if 26 4 92 5'4 I UnitedStates Patent 3,466,914 BENDING MACHINE David J. Gilchrist, Saginaw,Mich., assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Filed Nov. 12, 1965, Ser. No. 507,272 Int. Cl.B2111 7/024 US. Cl. 72214 8 Claims ABSTRACT OF THE DISCLOSURE Thisbending machine, in several automated steps, brings a pivotal clamp downagainst the stock to hold the stock against an arcuate bending surfaceof a die, advances a stock locator up to the die to permit bends closelyadjacent the locator, and moves a ram linearly past the die. The ramcarries a roller which forms the stock over the die while avoiding thepossibility of scratching the stock surface. The die overlaps a dieplate in such a manner that the force exerted by the bending processcannot cause the die to slip forward.

This invention relates to a machine for forming bends in cylindricalstock such as rods and tubes.

This machine is designed to permit rapid and accurate automatic formingof stock and to be readily adjustable so that it may be economicallyused for low volume production runs. The machine features an adjustablestock locating arrangement which permits complete control of the axiallocation of the bend and of the plane of the bend. This machineadditionally features a clamping arrangement which prevents movement ofthe end of the stock so that no force is transferred to the locatingpoints during the bending process. The machine also features a diemounting arrangement which provides rapid interchangeability ofdifferent size dies. The die mounting arrangement has an overlookingconstruction to prevent die movement during the bending process. Thecontrols of the machine are interlocked for safety of operation, theoperating cycle being automatic through the clamping process, providingfor manual actuation of the ram bending stroke, and providing automaticcompletion of the cycle.

The details as well as other objects and advantages of this inventionare disclosed in the following description and in the drawings in which:

FIGURE 1 is a front elevational view of the bending machine illustratingthe die, locator, and ram;

FIGURE 2 is a side elevational view along line 22 of FIGURE 1additionally illustrating the clamp;

FIGURE 3 is an enlarged view of a portion of FIG- URE 2 illustrating thedisposition of the clamp before the bending operation;

FIGURE 4 is a view similar to FIGURE 3 illustrating the disposition ofthe clamp after the bending operation;

FIGURE 5 is an enlarged sectional view of the locator illustrating itsmounting for radial adjustment and the switch which initiates automaticoperation of the machine;

FIGURE 6 is a schematic diagram of the hydraulic circuit for themachine;

FIGURE 7 is a schematic diagram of the pneumatic circuit for themachine; and

FIGURE 8 is a schematic diagram of the electrical circuit for themachine.

Referring first to FIGURE 1, the machine 10 is illustrated as having asingle bending stage. However, it will be appreciated that the machineis readily adaptable for additional stages of operation which may besimilar to that herein described.

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Machine 10 includes a base 12 which supports a die plate 14 and a die16. A ram carriage 18 and a locator carriage 20 are also supported onbase 12. As shown in greater detail in FIGURES 2 through 4, carriage 18is guided on rods 21 and moves a ram 22 linearly past die 16. Ram 22carries a roller 24 which engages and forces the stock 26 downwardly toform a bend over the arcuate bending surface of die 16. The rollingcontact of roller 24 with the stock 26 prevents scufling of the stock.

A clamp carriage 28 is also supported on the base 12. Carriage 28 isguided on rods 29 and advances a clamp 30 which is pivotally mounted bya pin 32. Clamp 30 has a pair of arcuate surfaces 34 and 36 which engagethe stock 26 and hold it against the arcuate bending surface of die 16.As shown in FIGURE 4, as the stock 26 is bent over die 16, clamp 30pivots to maintain a uniform clamping pressure on the stock. The arcuatecontour of the surfaces 34 and 36 permits rolling contact of clamp 30with the stock 26 and prevents marring of the finish on the stock.

Die 16 is secured to die plate 14 by a plurality of fasteners 38 and isthus readily removable so that another die of different radius may bequickly substituted. Die 16 is provided with an extension 40 whichoverlies the back portion 42 of die plate 14. Extension 40 and backportion 42 have cooperating surfaces which are angled, as indicated at44, to prevent forward movement of die 16 under the force of the bendingprocess.

The locator carriage 20 is axially positioned along its guide rod 46 toproperly locate the place of the bend along the length of the stock 26.As shown in FIGURE 4, locator carriage 20 supports a rim 48 within whicha locator 50 is positioned. Locator 50 may be rotated within rim 48 andsecured in a desired position by an adjustment piece 52. The rotativeposition of locator 50 is indicated by the markings 54 shown in FIGURE 3and may thus be accurately determined. A pair of indexing members 56within locator 50 cooperate with notches 58 in the stock 26;alternatively, indexing members 56 may cooperate with notches in acollar (not shown) appropriately secured about the stock 26. By such anarrangement, the radial position of the stock 26 may be adjusted so thatthe bend is formed in a proper plane whenever compound bends arerequired in the stock.

It will be appreciated from an examination of FIGURE 3 that it would bediflicult to place the stock 26 in locator 50 behind die 16 when thestock must be bent very close to the locator. For this reason, locator50 is provided with a pneumatic advance mechanism 60 (see FIGURE 2)which advances the locator toward the die after the stock has beenplaced within the locator. The automatic operation of advance mechanism61), as well as the automatic operation of the clamp and ram, isdescribed with further reference to the hydraulic circuit of FIGURE 6,the pneumatic circuit of FIGURE 7 and the electrical circuit of FIGURE8.

As shown in FIGURE 5, when the stock 26 is placed in the locator 50 itengages a button 62. The length of button 62 may be varied for differentlengths of the stock 26. Button 62 closes a switch S1 which connects asolenoid SOL1 across a suitable voltage source V. Solenoid SOL1 operatesa pneumatic valve 64 to direct air from an air pump to the chamber 66 atone side of a pneumatic piston 68. Piston 68 advances locator carriage20' to bring locator 50 up to the die 16.

Switch S1 also energizes a control relay CR1 which then closes itsinterlocks 70, 72, and 74. As locator 50 advances, it closes a switch S2which energizes a solenoid SOL2. Solenoid SOL2 operates a hydraulicvalve 76 which directs hydraulic fluid, delivered by a pump P from atank T, to a servo 78. Servo 78 operates a second by- 3 draulic valve 80to direct fluid to the chamber 82 at one side of a hydraulic piston 84.Piston 84 advances clamp carriage 28 causing clamp 30 to secure thestock 26 against die 16.

As piston 84 advances clamp 30, a switch S3 is opened from its Acontacts and closed across its B contacts to energize a control relayCR2. Relay CR2 then closes its interlocks 86, 88, 90, 92, and 94 andopens its interlock 96. Interlock 88 closes a circuit to a pair ofmanual switches M81 and MSZ which should be suitably disposed so that itis impossible for the machine operator to be in the way of the advancingram 22. When the operator actuates switches M81 and M52, closing theirC, D, E, and F contacts and opening their G and H contacts, a controlrelay CR3 is energized, closing its interlock 98 and opening itsinterlock 100. Interlock 98 energizes a solenoid SOL3 which operates ahydraulic valve 102. Valve 102 directs fluid to a servo 104 whichoperates another hydraulic valve 106. Valve 106 directs fluid to thechamber 108 at one side of a hydraulic piston 110. Piston 110 advancesram carriage 18 causing ram 22 to bend the stock 26 over the die 16.

A stop 112 is positioned on a portion of the ram mechanism to engage aswitch S4 when the stock 26 has been bent to a desired angle. Adjustmentof stop 112 permits control of the angle to which the stock 26 is bent.When switch S4 is closed by stop 112, a control relay CR4 is energizedto close its interlocks 114 and 120 and open its interlocks 116 and 118.Interlock 114 energizes a solenoid SOL4 to operate hydraulic valve 102and direct fluid to servo 122. Servo 122 operates hydraulic valve 106 todirect fluid to a chamber 124 at the opposite side of piston 110. Piston110 is thus re-energized to retract ram 22.

When ram 22 retracts, a switch S is opened fiom its I contacts andclosed across its K contacts. Switch S5 thus energizes a control relayCR5 which closes its interlock 126. Interlock 126 energizes a solenoidSOLS which operates pneumatic valve 64 to direct air to the chamber 128at the opposite side of pneumatic piston 68. Piston 68 is thusre-energized to retract locator 50.

When locator 50 retracts, a switch S6 is closed to energize a solenoidSOL6. Solenoid SOL6 operates hydraulic valve 76 to direct fluid to aservo 130. Servo 130 operates hydraulic valve 80 to direct fluid to achamber 132 at the opposite side of piston 84. Piston 84 is thusre-energized to retract clamp 30.

If it is necessary to suddenly retract clamp 30 before the end of thebending cycle, a manual switch M83 is closed to energize a control relayCR6 Which closes its interlocks 134 and 136 and opens its interlock 138.Interlock 136 energizes solenoid SOL6 which causes retraction of theclamp 30.

Timed relays TDI and TD2 are provided which delay a predetermined periodof time after energization before opening their interlocks 140 and 142to de-energize control relays CR3 and CR5. Solenoids SOL3 and SOLS thusremain energized only for the time necessary to operate valves 102 and64.

A series of simultaneously operated selector switches SS is providedwhich, in the indicated position across the L contacts, allows automaticadvance of locator 50. If automatic advance of locator 50 is notdesired, selector switches SS are switched to the M contacts. Theabovedescribed electrical and hydraulic circuits will then operate in asimilar manner'but solenoids SOLl and SOLS will be inactive.

The above-described electrical circuit provides a completely interlockedcontrol network in which the elements are energized only during the timea specific function is required. If the machine is operated incorrectlyor fails to perform properly, further operation is prevented. Thisarrangement is provided to make operation of the machine as safe aspossible.

From the foregoing, it will be appreciated that this machine is rapidlyand easily adjusted to form stock into a desired configuration; that thedie mounting arrangement and the clamp and ram operating modes provideaccuracy in the forming operation; and that the forming operation isperformed automatically and safely.

I claim:

1. A machine for forming bends in cylindrical stock comprising astationary die having an arcuate bending portion, clamp means adapted tohold the stock to prevent sliding movement of the stock relative to thedie, and ram means movable linearly relative to said die, said ram meansincluding a roller adapted to engage the stock by rolling contact andform the stock about the arcuate bending portion of the die.

2. A machine for forming bends in cylindrical stock comprising astationary die having an arcuate bending portion, clamp means adapted tohold the stock against said arcuate bending portion of said die toprevent sliding movement of the stock relative to the die, and ram meansadapted to form the stock about the arcuate bending portion of the die,said clamp means including a clamping portion mounted on a pivot, saidclamping portion rotating about said pivot to hold the stock againstsaid die as the stock is formed about said die.

3. The machine of claim 2 wherein said clamping portion includes a pairof surfaces each adapted to engage the stock.

4. The machine of claim 3 wherein each of the stockengaging surfaces onsaid clamping portion have an arcuate contour engaging the stock byrolling contact.

5. A machine for forming bends in cylindrical stock within a certainplane comprising a stationary die having a straight portion disposedwithin said plane for receiving the stock and having an arcuate portiondisposed within said plane about which the stock is bent, ram meansmovable within said plane for applying force to the stock in a directionwithin said plane to thereby form the stock about said arcuate portionof said die, clamp means for holding a portion of the stock against saidstraight portion of said die and tending to prevent movement of thatportion of the stock within said plane relative to said die whereby theforce applied by said ram means is transferred through the stock to saidstraight portion of said die in directions both perpendicular andtangential to said straight portion, and a stationary die plate having adie supporting portion disposed in said plane and oriented in adirection for absorbing the force transferred to said die in directionsboth perpendicular and tangential to said straight portion of said die,said die having a portion supported by said die supporting portion ofsaid die plate whereby force transferred to said die is transmitted toand absorbed by said die plate and whereby said die is prevented frommoving relative to said die plate.

6. A machine for forming bends in cylindrical stock comprising a diehaving an arcuate bending portion, clamp means adapted to hold the stockto prevent sliding movement of the stock relative to the die, ram meansadapted to form the stock about the arcuate bending portion of the die,and locating means adapted to surround the end of the stock toaccurately position the stock upon said die, said locating meansincluding automatic mechanism actuable upon insertion of the stock toadvance the stock up to said die whereby a bend may be formed in thestock closely adjacent said locating means.

7. The machine of claim 6 wherein said automatic mechanism comprises afirst electrical switch operable upon insertion of the stock into saidlocating means to energize a pneumatic piston which thereupon advancessaid locating means a predetermined distance toward said die and whereinsaid machine further includes automatic sequencing mechanism comprisinga second electrical switch operable upon predetermined advance of said10- cating means to energize a first hydraulic piston which thereuponadvances said clamp means to hold the stock,

a manual control, a third electrical switch operable upon predeterminedadvance of said clamp means to energize said manual control, said manualcontrol being operable to energize a second hydraulic piston whichthereupon advances said ram means to form the stock about said die, afourth electrical switch operable upon predetermined advance of said rammeans to re-energize said second hydraulic piston which thereuponretracts said ram means, a fifth electrical switch operable uponretraction of said ram means to re-energize said pneumatic piston whichthereupon retracts said locating means, and a sixth electrical switchoperable upon retraction of said locating means to re-energize saidfirst hydraulic piston which thereupon retracts said clamp means.

8. The machine of claim 6 which further includes a die plate having aback portion and wherein said die is mounted on said plate, said diehaving an extension overlying the back portion of said die plate toprevent movement of said die relative to said die plate, wherein saidclamp means includes a clamping portion mounted on a pivot, saidclamping portion rotating about said pivot to hold the stock against theface of said die and prevent sliding movement of the stock relative tosaid die, and wherein said ram means is movable linearly relative tosaid die and includes a roller adapted to engage the stock by rollingcontact to form the stock about the arcuate bending portion of the die.

References Cited UNITED STATES PATENTS 2,288,273 6/1942 Enghauser 72214RONALD D. GREFE, Primary Examiner US. Cl. X.R. 72386

